Diffraction grating

About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.

Self-diffraction of continuous laser radiation in a disperse medium with absorbing particles

Abstract: We study the self-action of light in a water suspension of absorbing subwavelength particles. Due to efficient accumulation of the light energy, this medium shows distinct non-linear properties even at moderate radiation power. In particular, by means of interference of two obliquely incident beams, it is possible to create controllable phase and amplitude gratings whose contrast, spatial and temporal parameters depend on the beams’ coherence and power as well as the interference geometry. The grating characteristics are investigated via the beams’ self-diffraction. The main mechanism of the grating formation is shown to be thermal, which leads to the phase grating; a weak amplitude grating also emerges due to the particles’ displacements caused by the light-induced gradient and photophoretic forces. These forces, together with the Brownian motion of the particles, are responsible for the grating dynamics and degradation. The results and approaches can be used for investigation of the thermal relaxation and kinetic processes in liquid suspensions.

Silicon Photonics Core-, Wavelength-, and Polarization-Diversity Receiver

Abstract: A seven-core optical fiber, each core carrying two wavelength channels, is coupled to a novel silicon photonic integrated circuit (PIC). The silicon PIC uses grating couplers, Mach-Zehnder interferometers, and photodiodes to demultiplex and receive all 14 signals. We demonstrate reception of polarization-scrambled 5-Gb/s on-off keyed signals.

Polarization selective spectroscopy experiments: methodology and pitfalls

Abstract: We analyze the effectiveness of various practical implementations of time-dependent pump-probe and transient grating polarization-selective experiments. A variety of optical arrangements are analyzed in the Jones matrix calculus framework. The optical arrangements that permit the correct determination of the time-dependent orientational and excited-state population dynamics are delineated. It is shown that magic angle transient grating experiments yield pure population dynamics under certain conditions only. The effectiveness of spectrally resolved magic angle pump-probe and transient grating experiments that use a monochromator are shown to be dependent on the position of an analyzing polarizer along the experimental beam path relative to various other optical elements. The spectrally resolved experiments will measure pure population dynamics only if a polarizer is placed immediately after the sample. The effectiveness of experiments measuring orientational dynamics by separately measuring the probe signal with its polarization parallel and perpendicular to the pump polarization is not constrained by the conditions imposed on the magic angle experiments.

High-efficiency, broad band, high-damage threshold high-index gratings for femtosecond pulse compression

Abstract: High efficiency, broad-band TE-polarization diffraction over a wavelength range centered at 800 nm is obtained by high index gratings placed on a non-corrugated mirror. More than 96% efficiency wide band top-hat diffraction efficiency spectra, as well as more than 1 J/cm(2) damage threshold under 50 fs pulses are demonstrated experimentally. This opens the way to high-efficiency Chirped Pulse Amplification for high average power laser machining by means of all-dielectric structures as well as for ultra-short high energy pulses by means of metal-dielectric structures.

Angular tolerant resonant grating filters under oblique incidence.

Abstract: Resonant grating filters have been proposed as a promising alternative to multilayer stacks for narrowband free-space filtering. The efficiency of such filters under normal incidence has been demonstrated. Unfortunately, under oblique incidence, the limited angular tolerance of the resonance forbids any filtering applications with use of standard collimated incident beams. Using a multimode planar waveguide and a bi-atom grating, we show how to increase the angular tolerance up to the divergence of standard beams (0.2 deg) without modifying the spectral bandwidth (0.1 nm), under any oblique angle of incidence.